Types of Blockchain

Following are the major types of blockchain networks:

1. Public Blockchain Network Anyone can read or write a transaction to the network, or participate in the consensus process. They are considered to be "permissionless". Every transaction is on the public network with privacy of encrypted data, which helps user's remain pseudonymous. Caduceus and Ethereum are good examples of public blockchains.
2. Private Blockchain Network Private Blockchain are run and controlled by a single organisation that determines who can read, write and participate in consensus process. Since they are 100% centralised, private blockchain is useful for sandbox environments and not for Production.
3. Semi-private Blockchain Network This network is run by a single company that grants access to any user who satisfies a pre-established criteria. Although it's not truly decentralised, this solution is appealing to business-to-business use cases and government applications.
4. Consortium Blockchain Network In a consortium blockchain, the consensus process in handled by a group of people. The right to read and write maybe public or restricted to a participant. Consortium blockchains are considered to be "permissioned blockchains" and best suited for organisations and enterprises.

Extra links​

📄 Public vs Private Blockchain: A comprehensive comparison 📖 On Public and Private Blockchain, Vitalik Buterin